(a) Field of the Invention
The present invention relates to a locking mechanism for the head tube of a bicycle, particularly one using a stop member to cooperate with two push members so that the vertical tube can be locked together tightly with the head tube.
(b) Description of the Prior Art
A conventional design of the locking mechanism for the tube of a bicycle is shown in FIG. 5. The mechanism uses a push plate 10 (the back of which is provided with a cylindrical body 101 having slanted surface) to cooperate with a push member 20 (also formed with slanted surface) and a bolt 30. When the bolt 30 is fastened, the push member 20 pulls downward, thus the slanted surface of the push member 20 comes in contact with the slanted surface of the cylindrical body 101 of the push plate 10, allowing the push plate 10 to push forward for locking. However, the force from the bolt to the push plate 10 comes from a vertical direction, thus it is distributed and cannot be applied efficiently. Also, the force cannot be uniformly applied.
Another type of conventional locking mechanism for the head tube of a bicycle is shown in FIG. 6. The bottom side wall of the vertical race 401 of the head tube 40 is provided with a groove for a holding member 50 to be placed therein, and a bolt 60 is used for locking. When the bolt 60 is fastened, the holding member 50 is pulled upward, allowing the side of the holding member 50 to move forward to come in contact with the vertical tube. However, this structure also uses a unique holding member and there is no assurance that the holding member will move upward. Therefore, a minor offset of the holding member will cause it to come in contact with the vertical tube, causing the locking force to be applied to a single point.